The drive for wireless communications is to allow for greater levels of roaming and allow seamless roaming. Myriad issues, such as hand-off between providers, authentication, communication system capabilities and limitations, become increasingly important when roaming, particularly when global roaming is contemplated.
When a mobile node moves from an area covered by one network and enters another area covered by another network the call must be transferred to the second network without dropping the connection or loosing packets. This function can be referred to as handover with fast mobility. Similarly, when a mobile node is powered on in a new location served by a different network than the immediately preceding network used by the mobile node, the wireless communications network must recognize the change in location of the mobile node and direct to the new network the information destined to the mobile node. This can be referred to as handover with slow mobility. Wireless communications networks must support such slow-mobility roaming and fast-mobility handoff or handover to enable seamless mobility of mobile devices.